GETTING PAST THE ‘YUCK’ FACTOR
Auckland needs to look at reusing wastewater — city boss
If climate and population trends persist, Aucklanders could one day be drinking treated sewage water — if they can get over the “yuck” factor.
For Watercare chief executive Raveen Jaduram it is less a case of if, than when, and he says the city needs to start “mature” conversations about the potentially taboo topic right now.
Amid the worst drought on record, Auckland Council this week signed off mandatory restrictions for the first time since 1994, when the region’s supply dams dropped as low as 29 per cent.
Then, there was no emergency drought back-up, and in response the council sought consent to supplement its dams by taking 150 million litres a day (MLD) from the Waikato River.
But despite Watercare taking as close to its full take from the Waikato as possible since January, the dams this year have still dropped to 45 per cent in the driest January to April period on record, with one run of 77 days without rain.
The region has experienced drought in three of the past four
years, and six in the past 10, according to Niwa.
Meanwhile, the city grows — more than 50 per cent since 1994 — and with climate change bringing increasingly dry summers, Auckland’s thirst increases as the supply shrinks.
When full, the dams in the Hunua and Waita¯kere ranges — the region’s rainmakers — contain about eight months’ water for the city’s 1.6 million inhabitants, generally providing about two-thirds of daily usage, which averages about 450MLD a day.
Smaller aquifers and bores also assist, but without any major underground sources and no desire to further dam the ranges, the council applied to take a further 200MLD from the Waikato River in 2013.
Under the Resource Management Act, such applications are “first-in, first-served”, meaning the council sat at around 200 in line.
It has since risen to about 94 — but this week Auckland mayor Phil Goff called that process “unacceptable”, and revealed he’d written to Environment Minister David Parker that the system needed to be changed.
Jaduram estimates based on population growth and climate projections the city will need that extra supply by about 2025, perhaps a little later.
That supply will suffice for at least another decade — but beyond then Jaduram says Auckland needs to start looking at “circular” options, such as reusing wastewater. Desalination was also an option, but it was very energy intensive and expensive.
“Treating wastewater is the most environmentally friendly and preferable option. It is a closed loop system, though it presents some societal challenges — the ‘yuck factor’.”
It is used in about 35 cities around the world, and in parts of the United States since the 1960s.
In Perth, about 14 billion litres of recycled water is added to the city’s aquifers every year, and that will double next year.
In practice, Auckland’s water coming out of the Ma¯ngere wastewater treatment plant would be given further treatment, passed through a range of filters — such as aquifers or wetlands — before getting another round of treatment to ensure it was at a drinkable standard.
“It is normal in many places around the world, Singapore is leading the way,” Jaduram said. “If there is nothing else, what do you do?”
Legislation would need to change to allow it here, as would society’s views, he said.
Toowoomba in central Queensland is a case in point. The community rejected the idea, despite it being common in other parts of Australia.
“But water is going to become a bigger issue. There is a view that New Zealand has a lot of water, but areas like Auckland will be seeing less rain with climate change.
“It’s not the distant future — it is happening now, and we need to be having these mature conversations.”
Other ideas include rain-water tanks on all new builds and promoting grey-water systems, to store water and ease pressure on the stormwater network. Jaduram said they would help, but not in times of drought.
“This summer we’ve seen all of those on tank supply needing to be refilled from the city supply. The problem is they also run out when it doesn’t rain.”
The idea could run into opposition from tangata whenua.
University of Auckland freshwater and Ma¯ori studies expert Dan Hikuroa said Ma¯ori tikanga opposed mixing of
waimate — water devoid of life — and waiora — fresh, healthy water.
But he didn’t see treated wastewater as waimate. “It is degraded, but it is not dead water.”
Hikuroa — of Nga¯ti Maniapoto, Tainui and Te Arawa — is part of Watercare’s environmental advisory team, and said the ability to recycle wastewater came down to ensuring the mauri, or life-supporting capacity, was restored.
“That is done by passing it through Papatu¯a¯nuku, the earth.”
The idea stems from springs, where water had been naturally filtered through the earth, and which historically Ma¯ori held in high regard for its mauri.
“There is nothing more pure and life-supporting than that. So pragmatically speaking, we’d want it to be scientifically treated, and then passed through a sort of earth-based treatment.
“We’d probably be looking at it being used in more industrial processes first though, that’d be an easier hurdle.”
In the meantime, Hikuroa said people needed to treat water with more care.
“We need to treat the whole system as taonga, look to conserve and collect as much as we can.”
This was consistent with Watercare’s messaging, with Jaduram saying conservation would delay needing to increase supply.
He acknowledged this was already relatively low, with residents averaging about 157 litres a day, compared to 263 nationally, but every bit counted.
Other measures to investigate were signals and tariffs, such as increasing the price in summer to discourage excessive use.